Acids & Bases Introduction.ppt for businees stufeens
- 1. Prepared By, Mrs Yap- Wong Fui Yen
- 3. Some everyday things that contain acids
- 4. In fact, we even have acid in our stomach!!!
- 5. Sharp and sour taste. Corrosive pH less than 7 What properties do acids have in common?
- 6. An acid is a substance that produces ___________ when it dissolve in water. What is the meaning of acids? hydrogen ions,H+
- 7. • Acids only produce hydrogen ions in water. water without water •Acids only show the properties of acids when they are dissolved in water.
- 8. • It is the hydrogen ions which are responsible for acidic properties. • This is because acids ionise in water. add water
- 9. Common acids: Formula: Ions produced: Hydrochloric acid HCl H+ and Cl- Sulphuric acid H2SO4 H+ and SO4 2- Nitric acid HNO3 H+ and NO3 -
- 10. Experiment I: The pH Scale
- 11. What is the pH Scale? A scale which measures the degree of acidity or alkalinity of an aqueous solution. Ranges from 0 – 14.
- 12. pH of some common substances: Increasing Acidity Increasing Alkalinity Neutral 1 2 3 4 5 6 7 8 9 10 11 12 13 pH = 14 pH = 0 “Pure water” HCL Lemon Juice , Vinegar Detergent Sodium hydroxide Ammonia Sea water Baking Soda Soap Orange Juice Acid Rain Urine Soft drink, Black Coffee
- 13. 1 2 3 4 5 6 7 8 9 10 11 12 13 pH = 14 pH = 0 Solutions of pH less than 7 is acidic. The smaller the pH, the more acidic. Solutions of pH greater than 7 is alkaline. The bigger the pH, the more alkaline. Solution of pH 7 is neutral “Pure water” HCl Sodium hydroxide Detergent Soft drink
- 14. Common pH indicators: Universal Indicator Litmus paper Phenolphthalein Methyl orange Different colours are observed in solutions depending whether it is:- acidic alkaline.
- 15. ACIDS 1. Metals 2. Carbonates 3. Metal Oxides And Hydroxides (Neutralisation) reacts with Type of Reactions of Acids:
- 16. Dilute hydrochloric acid (HCl) Magnesium ribbon Acid Metal Hydrogen Salt Reaction 1: Acid with metals + +
- 17. Acid used: Salt produced: Hydrochloric acid Chloride Sulphuric acid Sulphate Nitric acid Nitrate Carbonic acid Carbonate
- 18. Magnesium + hydrochloric magnesium chloride acid + hydrogen Mg + 2HCl ----> MgCl2 + H2 Example: Test: Use a burning/lighted splinter to test hydrogen gas. Result: A ‘pop’ sound is heard
- 19. Reaction 2: Acid with carbonate Acid carbonate salt carbon dioxide + + water +
- 20. Word Equation: calcium + hydrochloric calcium chloride carbonate acid + carbon dioxide + water Chemical Equation: CaCO3 + 2HCl CaCl2 + CO2 + H2O Example (2a):
- 21. copper(II) oxide + hydrochloric copper(II) cloride acid + water CuO + 2HCl ------> CuCl2 + H2O Reaction 3: Acid with metal oxide/ hydroxide Acid + Metal oxide /hydroxide salt + water This reaction is also known as “neutralisation”.
- 22. Summary (a) Acid and Metal metal + acid salt + hydrogen (b) Acid and Carbonate carbonate + acid salt + water + carbon dioxide (c) Acid and Metal Oxide/ Hydroxide (Neutralisation) acid + base salt + water
- 23. Not done yet! So,what are the common alkalis used in our daily life?
- 24. Some everyday things that contain alkali
- 26. Perming solutions contain alkali which makes hair curly
- 27. Baking powder is alkaline
- 28. pH >7 Bitter taste. Soapy feeling to the skin. What properties do bases have in common?
- 29. solution of hydroxide ions, OH-are produced when bases dissolve in water. NaOH Na+ + OH- Ca(OH)2 Ca2+ + 2OH – What is the meaning of bases?
- 30. Most bases are insoluble in water. Bases that dissolve in water/ soluble are called alkalis. Insoluble bases Soluble bases Magnesium oxide Sodium hydroxide Copper(II) oxide Calcium hydroxide Iron(II) oxide Ammonia Is base similar to alkaline?
- 31. BASES 2. Ammonium Salts 1. Acids (Neutralisation) reacts with Bases reactions
- 32. 1. Neutralisation reaction Bases reacts with an acid to produce a salt and water ACID + BASE --> SALT + WATER HCl + NaOH -----> NaCl + H2O
- 33. Write a word and symbol equation when sulphuric acid react with sodium hydroxide? H2SO4 + 2NaOH Na2SO4 + 2H2O
- 34. 3. Alkali reacts with an ammonium salt. Ammonium + sodium sodium chloride chloride hydroxide + water + ammonia gas NH4Cl + NaOH --> NaCl + H2O + NH3 •Ammonia gas is produced.
- 35. Importance of pH: pH of food pH of soil pH of tank
- 36. pH & Agriculture pH of soil •Excess acid in the soil can be neutralised by adding calcium hydroxide (slaked lime). • Farmers spread calcium hydroxide powder over their fields to neutralise acids.
- 37. CHEMICAL NAME FORMULA DISSOLVE IN WATER FOUND IN/USED FOR Sodium hydroxide NaOH Yes Alkali pH 13 Used to make soap. Ammonia NH3 Yes Alkali pH 10 • The main active ingredient in household cleaning fluids. Calcium hydroxide Ca(OH)2 Yes Alkali • Used in agriculture to neutralise acidic soils. Aluminium hydroxide Al(OH)3 No Base • Used in some indigestion tablets.